<?php
/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_InfoCard
 * @subpackage Zend_InfoCard_Xml
 * @copyright  Copyright (c) 2005-2008 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 * @version    $Id: Exception.php 2794 2007-01-16 01:29:51Z bkarwin $
 * @author     John Coggeshall <john@zend.com>
 */

/**
 * Zend_InfoCard_Xml_Element
 */
require_once 'Zend/InfoCard/Xml/Element.php';

/**
 * Zend_InfoCard_Xml_KeyInfo
 */
require_once 'Zend/InfoCard/Xml/KeyInfo.php';

/**
 * An abstract class representing a generic EncryptedData XML block. This class is extended
 * into a specific type of EncryptedData XML block (i.e. XmlEnc) as necessary
 * 
 * @category   Zend
 * @package    Zend_InfoCard
 * @subpackage Zend_InfoCard_Xml
 * @copyright  Copyright (c) 2005-2007 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 * @author     John Coggeshall <john@zend.com>
 */
abstract class Zend_InfoCard_Xml_EncryptedData_Abstract extends Zend_InfoCard_Xml_Element 
{
	
	/**
	 * Returns the KeyInfo Block
	 *
	 * @return Zend_InfoCard_Xml_KeyInfo_Abstract
	 */
	public function getKeyInfo() 
    {
		return Zend_InfoCard_Xml_KeyInfo::getInstance($this->KeyInfo[0]);
	}
	
	/**
	 * Return the Encryption method used to encrypt the assertion document 
	 * (the symmetric cipher)
	 *
	 * @throws Zend_InfoCard_Xml_Exception
	 * @return string The URI of the Symmetric Encryption Method used
	 */
	public function getEncryptionMethod() 
    {
		
		/**
		 * @todo This is pretty hacky unless we can always be confident that the first
		 * EncryptionMethod block is the correct one (the AES or compariable symetric algorithm)..
		 * the second is the PK method if provided. 
		 */
		list($encryption_method) = $this->xpath("//enc:EncryptionMethod");

		if(!($encryption_method instanceof Zend_InfoCard_Xml_Element)) {
			throw new Zend_InfoCard_Xml_Exception("Unable to find the enc:EncryptionMethod symmetric encryption block");
		}
		
		$dom = self::convertToDOM($encryption_method);
		
		if(!$dom->hasAttribute('Algorithm')) {
			throw new Zend_InfoCard_Xml_Exception("Unable to determine the encryption algorithm in the Symmetric enc:EncryptionMethod XML block");
		}
		
		return $dom->getAttribute('Algorithm');
	}
	
	/**
	 * Returns the value of the encrypted block
	 * 
	 * @return string the value of the encrypted CipherValue block
	 */
	abstract function getCipherValue();
}
